The objective of the present invention is to provide a feeding arrangement enabling detection of the movement of a single phase stepping motor, as used for instance in a timepiece, and arranged to control the operation of the motor by supplying a first type of bipolar pulses of short duration or by supplying a second type of bipolar pulses of greater duration, a pulse train of the second type being fed to the motor in the event that the motor has failed to step in response to a short duration pulse.
Arrangements of this general nature are known and in order to overcome difficulties which may occur the applicant has proposed a new solution to the several problems in his U.S. application Ser. No. 162,227 and which claims an arrangement including a step detector having first means arranged to sample a first signal Ud developed by the current through the motor winding and second means arranged and adapted to generate a second signal ##EQU1## the level of which indicates whether or not the motor has stepped in response to a pulse of the first type.
The above mentioned patent application proposes two possible means for sampling the first signal Ud developed by the current in the motor winding.
One detection means comprises a bridge of which one of the branches is constituted by the motor winding, one of the diagonals being fed by the motor pulses and the other diagonal providing the signal Ud. If this system presents certain advantages over those proposed by the state of the art it presents the difficulty of sampling only a very low voltage (on the order of 20 mV) this being the difference between two relatively high voltages (on the order of 1.5 V). Since the temperature coefficients of the resistance of the motor winding and that of the other resistances in the bridge are not the same it can be shown that the arrangement will not function reliably over an extended temperature range (for example -10.degree. C. to +60.degree. C.)
Another detection means proposed by the above mentioned application comprises a sensing winding inserted into the magnetic circuit of the motor, the voltage developed at the terminals of this winding providing a signal Ud. This signal has the advantage of eliminating the resistance bridge mentioned above as well as the losses which are brought about thereby, and if the winding comprises a sufficient number of turns the voltage obtained will be of an amplitude more easily detectable than that which occurs on the diagonal of the bridge. This arrangement however has the inconvenience of necessitating an auxiliary winding in the magnetic circuit of the motor thus increasing the manufacturing cost and complicating moreover the wiring within the watch.
It is the purpose of this invention to eliminate the difficulties mentioned above and to obtain a feeding arrangement which, although based on the general principal described in the cited patent application, proposes new means for sampling the signal Ud at the motor winding terminals.
This purpose is realised by use of the means as claimed.